Robust Tension Control of Strip for 5-Stand Tandem Cold Mills

Behrooz Shafiei,Khoshnam Shojaei,Mohsen Ekramian

doi:10.1155/2014/409014

Abstract

Tandem cold rolling process is a nonlinear complex system with external and internal uncertainties and significant disturbances. The improvement in the quality of the final output depends on the control strategy of centerline thickness and interstand tension. This paper focuses on interstand tension control problem in 5-stand tandem cold rolling mills. Tension dynamics can be described by a nominal model perturbed by parametric uncertainties. In order to overcome the model uncertainties and external disturbances, suboptimalH∞andμcontrollers are proposed and the Hankel-norm approximation is used to reduce the order ofμcontroller. The performance of the proposed controllers is demonstrated by some simulations.

Highlights

The production of cold rolled coils typically consists of separate processes such as annealing, pickling, cold rolling, and skin pass rolling
Tandem cold mill (TCM) is one type of cold rolling processes that strip thickness reduction is achieved with a number of nonreversing stands
In tandem cold mill (TCM), strip passes through individual pairs of work rolls

Summary

Introduction

The production of cold rolled coils typically consists of separate processes such as annealing, pickling, cold rolling, and skin pass rolling. Tandem cold mill (TCM) is one type of cold rolling processes that strip thickness reduction is achieved with a number of nonreversing stands. The production of this process can be applied for various industries such as food packaging, automobile manufacturing, and home appliance [1, 2]. Tension control is one of the most important process parameters in tandem cold mill (TCM). There are numerous uncertainties and disturbances in the model of tandem cold rolling process [14].

Interstand Strip Tension Overview

Robust Tension Controller Design

Simulation Results

Conclusion

V: Work roll linear velocity UV: Speed actuator input τV